Alzheimer's disease is a medical illness that damages the brain and causes problems with memory, mood and behavior. A substance called acetylcholine (ACh), which is naturally produced in the body, plays an important role in the normal functioning of the brain. In subjects with Alzheimer's disease, the level of ACh is greatly reduced. Currently, there are three commonly prescribed drugs used for treating the symptoms of Alzheimer's disease by helping to maintain the level of ACh in the brain. This study will evaluate how much each of these drugs changes the levels of certain brain chemicals that are known to, or may play an important role in, Alzheimer's disease and its symptoms.

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study.
To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below.
For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00104442